#lang racket


(provide current-in-backend
         set-current-in-backend!
         
         current-out-backend
         set-current-out-backend!)


(define current-in-backend #f)

(define (set-current-in-backend! backend)
  (set! current-in-backend (make-parameter backend)))
         
         
(define current-out-backend #f)

(define (set-current-out-backend! backend)
  (set! current-out-backend (make-parameter backend)))